• - Fabric
  • - Lining
  • - Thread
  • - Buckram
  • - Wadding
  • - Weights
  • - Curtain Hooks
  • Tools
  • - Sewing Machine
  • - Needles
  • - Pins
  • - Clamps
  • - Scissors
  • - Set Square
  • - Straight Edge
  • - Invisible Marker
  • Step 3: Calculate Fabric Quantity
    Printable Worksheet
    Printable Worksheet

    Fabric is ordered in a length of metres cut from the roll. Before calculating fabric quantities you will need the following:

    With this information we :

    • Calculate the NUMBER OF WIDTHS OF FABRIC required to make the pair of curtains
    • Calculate the FABRIC CUT DROP
    • Then Calculate* the amount of FABRIC REQUIRED.

    * Note: The final calculation depends on whether the fabric is PLAIN or has a PATTERN.


    To calculate the number of fabric widths required to make your curtains:

    • Multiply Pole Length by Fullness Ratio.
    • Divide this figure by the Fabric Width.
    • Round the result up or down to the nearest whole number*.
    • This whole number is the number of widths you require to make your curtains.
    * Note: When rounding up or down you are slightly increasing/decreasing the fullness of your curtains. Rounding down results in less full curtains and if using a fullness ratio of 1.9 the curtains can be too thin if you round down.


    To calculate the Fabric Cut Drop

    * We also add a 5cm trimming allowance for PLAIN FABRIC to enable us to straighten the ends of the cut lengths, we dont for PATTERN FABRIC as there is usually extra fabric in the ADJUSTED CUT DROP.

    PLAIN and PATTERNED FABRIC are treated differently at this stage


    To calculate the amount of plain fabric required to make a pair of curtains:

    • Multiply the "Number of fabric widths" by Fabric Cut Drop.

    Alternatively try our online calculator.


    This tutorial is based on a normal pattern repeat fabric, if your fabric has a half drop pattern repeat please read HERE and adjust the instructions accordingly.

    When the fabric has a pattern we also have to take into account that the pattern will need to line up where we join fabric and the pattern will need to be in the same position on each curtain.

    To enable this we adjust the fabric cut drop so we can get a cut drop starting at the same pattern position each time.


    To calculate the Adjusted Cut Drop:

    • Divide the Fabric Cut Drop by the vertical Pattern Repeat
    • Round the result up to the nearest whole number
    • Multiply the whole number by the vertical Pattern Repeat
    • You now have the Adjusted Cut Drop (ACD)
    • The Adjusted Cut Drop is also a whole number of vertical pattern repeats, note this number down for use in measuring cut drops in step 6.


    To calculate the amount of patterned fabric required to make a pair of curtains:

    • Multiply the "Number of fabric widths" by Adjusted Cut Drop.
    • Add one vertical pattern repeat (this allows you to choose where the pattern starts)

    Alternatively try our online calculator.

    This video explains
    • The difference between half drop pattern repeat and normal pattern repeat
    • Adjusted cut drop

    Extra Help & Comments

    Sew Helpful
    Post your questions and comments here, we will reply so everyone can see the answer.
    HI - Have made 13 blinds with your great tutorials...moving on to curtains now. Just quick question re fabric widths don't mention return to wall measurements in the calculation above....I'm assuming I need to include this when calculating the fabric widths?
    Sew Helpful
    Yes the calculation is based on not using a return. You are really looking for the number of widths / half widths you want to make each curtain with so there is leaway in the figures (note we dont include the 8cm overlap). But if you are using returns it would probably be best to add them to the pole length.

    I will adjust the instructions and add a note.

    Thanks for the feedback. 
    Hi - I've just made some edged Roman Blinds using your great tutorial and now starting to make matching patterned Curtains trimmed with a plain fabric 20cm wide leading edge but am having trouble working out how much fabric I need (i.e. how many fabric widths) to account for the additional edging. I haven't decided whether to make double or triple pleats but am working on a fullness of 2.25 and will adjust fullness (and therefore pleats) to be most efficient with fabric
    Pole length: 220cm
    Finished Curtain width: 118cm
    Fullness Ratio: 2.25cm
    Fabric width: 137cm (both plain and patterned)
    Using your calculator, it suggests I would need 3.6 widths (rounded up to 4) but this doesn't account for the edging.

    Is there any easy way to work out what I need or do I have to do it long-hand? If so, am I right to assume that the required fabric width is the finished curtain width X Fullness ratio plus any seam allowances?? (118 x 2.25 = 265.5 plus allowances approx 25)

    Using this assumption, I think that I will probably need 1.8 widths of pattern for each curtain PLUS the plain edging. If I am right, should I add the narrow edge to 1 x full width plus 0.8 width OR 2 x 0.9 widths? Which would look best? If 1 + 0.8 is advised, which should be the central panel?
    Grateful for your advice - thank you
    Sew Helpful
    We would use a minimum fullness ratio of 2.5 for triple pleats, If you are using 2.25 we would make double pleats working on approx 6 pleats per width.

    I'm afraid you have to do the calculations long hand and work it all  out. The seam allowances are included within the fullness ratio. The only thing you may need to add to the pole length are returns if you are having them on your curtains.

    Rather than specify a trim leading edge width at the start we would actually work out our pleats and spacing first, then calculate the width of the trim so it finishes at the right place on the curtain. ie at the first pleat, halfway through the first pleat, at the end of the first pleat etc.. rather than at a random place on the curtain.

    We would join the trim to the patterned fabric (note the trim fabric will have to include fabric for the join seam with the pattern, side turn and the depth of trim). We would then cut the panel down to the width we required taking excess fabric from the other side not the trim side. Of course your extra trim fabric could be making your panel up to the panel width you want so you may not need to cut it down.

    Hi I'm making with a fullness of 1.9, I've come up with fabric widths required of 4.456! Do you think I can get away with just 4 widths? I don't want the curtains to be too full or too 'bunched up' when open. Do you think I can get away with 4 widths? Pole length of 326cm!

    Sew Helpful
    It would be minimal, We would make up a dummy header and see what it is like before proceeding.
    I am making small double pleat curtains for a boat. Measurements are W45cm L 60cm. do I really need a hem allowance of 16cm? Also should I still use 1.9 ratio?

    Many thanks
    Sew Helpful
    No the 16cm is just what we use for sill length curtains in a house. You can make the hem any size you like.

    We would probably go for less than 1.9 for that curtain. Initially thinking of using 5-6cm pleats with 10-9cm gaps. We would make a quick mock up and see if that looks right. 
    Jill sharp
    Hi I am making interlined double pinch pleat curtains, I am using 3 widths in each curtain can you tell me where the seams should sit, should they sit inside the pleat or on the flat area between a pleat and also how much spring back should I allow per curtain. Also will the flat area on the inside edges be enough to cover the middle bracket on the pole so not to leave agap in middle when curtains are closed
    Sew Helpful
    We tend to have the seam in a gap rather than the pleat to avoid bulk in the pleat.

    in STEP 2 when calculating the finished curtain width we add 8cm to each curtain for ease and overlap.

    We don't know how big your bracket in the middle is, so you will need to work out what size leading edges you need (to cover this area where there will be no rings) in STEP 9 when working out your pleats.
    Hi I'm making one pair of one and half width curtains and one pair of half width curtains can you tell me how to calculate how much triple pleat curtain tape I would need
    Sew Helpful
    I'm afraid we dont make calculations for people.

    STEP 8 of the tutorials show you how much buckram or tape  we use. 

    We only use tape in the pencil pleat tutorial, the others including triple pleat are hand made headings with buckram. 
    Hi, I am concerned about 'Spring back' on the dbl pinch . Does the '8cm' added to half the pole length allow for this?
    Sew Helpful
    The 8cm is what we use for this but you can allow more if you like.
    Lynn Nunn
    How much fullness do I need fod a hand sewn french pleat valance with a finished width of 145cm plus 15cm x 2 for the returns?
    Sew Helpful
    If we are unsure if the usual fullness ratio is going to work with larger returns etc, we calculate slightly differently. We make a sample pleat the size we want it and see how much fabric that pleat requires. We then work out the  number of pleats+spaces and space sizes we are going to use. From that info (including your return sizes) we know what width panel we need to make, to pleat up.
    Hi, looking at making a valance but my window is 4 metres long and dont know how much fabric i need. they siad it is 137cm wide and has a pattern repeat of .34cm

    Sew Helpful
    I'm sorry we don't calculate fabric quantities. 
    Hi sorry this is going to sound a very basic question. Just trying to work out if we have enough material for double pleat curtains and it states a fullness ratio of 1.9-2.2.... what does this even mean? is it you're stating i need to add an additional 1.9-2.2 for each curtain on top of each curtain measurement. Or an additional 1.9-2.2 on the whole window size, or some other thing that I'm just not getting..sorry just a bit confused(I'm a man lol) as to what i'm adding 1.9-2.2 to. Basically I have been given a pair of very expensive, fantastic triple pleated silk curtains, which are huge and i'm trying to work out if there is enough material in them to make curtain for my 4 windows with the material. Thank you
    Sew Helpful
    When you make a curtain you effectively make a flat panel then you pleat it up , that panel becomes narrower at the heading where the pleats have pulled it together. If you were making a curtain that was to be 1m wide when it was pleated with a fullness ratio of 2.2 You would need a panel 2.2m wide before you pleated it up to make it 1m wide.
    Thank you for your reply :-)
    Thank you for these tutorials - very helpful indeed. I have given myself a problem with the curtains I'm making by not making them long enough to include the 5 " buckram heading I need (I changed my mind about the type of curtains I was making - not very wise!). However, I do have about an inch extra length (after finished curtain length) so I am thinking of extending the curtains by sewing and extra panel across the top which will then be hidden in the buckram fold and not visible from the front. Do you think this could work or should I just give up? Many thanks for your advice.
    Sew Helpful
    Yes that should work, You could even join lining to the top if it is only going to be on the back. We have done this before with expensive fabrics and large pattern repeats to save the customer a lot of fabric costs.
    Thank you! Very encouraging!
    I have had made to measure double pleat curtains,do I need a special curtain track as they are not sitting well on my swish track?
    Sew Helpful
    They might be being pushed forward between pleats when stacked back as it is a track. See the video in STEP 1 (it's free), we talk about where to put the pin and how they stack back.
    Hi,love your website so helpful.

    Will you be putting up calculations for eyelet curtains any time soon?
    Sew Helpful
    Eyelets are on the list but I'm afraid they're a long way down
    Hi there.

    My first attempt and double pleats and I forgot to allow for the buck rum depth in my calculation of fabric cut drop. Lengths are cut unfortunately for the first curtain and I don’t have enough excess in the middle panel. Could I hem the top and add the buckram over it and pleat?
    Sew Helpful
    You can sew a strip of lining to the top of the fabric to fold over the buckram.
    Does the 20 cm hem allowance for full length curtains include the bottom hem and the side hems? Also, do we account for seams of sewing the widths together? Thank you...
    Sew Helpful
    No and No

    The unusable selvedge edge of the fabric usually accounts for most of the seam allowance when joining.
    I am making large curtains ( 3 widths in each curtain)with a appx. 2.5 metre drop. My working bench is reasonable size but not as big as each curtain!!! Can you give any advice on how to handle such large quantities of fabric and still get good results?
    Sew Helpful
    It will be hard work, keep it all as flat and smooth as you can when working on it, Clamps are very good for holding sections in place on the table, if you havent got clamps you can use weights. Spring clamps are pretty cheap on ebay though (make sure you dont buy tiny ones though)
    Lucie Rees
    I have a question about the required widths of fabric. Is the amount required for each panel or is it the amount required for the window if making two panels? I am making two panels for my window and based on calculations, I need 2 widths of fabric. I am unsure if that is for each panel or if each panel requires 1 width. Thanks!
    Sew Helpful
    The number of widths calculated is what is required to make both curtains if you are making a pair to cover the window, or a large single curtain if you are not making a pair.

    For simplicity the tuorial and it's examples are based on making a pair of curtains to cover the window.
    Lucie Rees
    I have a question about the required widths of fabric. Is the amount required for each panel or is it the amount required for the window if making two panels? I am making two panels for my window and based on calculations, I need 2 widths of fabric. I am unsure if that is for each panel or if each panel requires 1 width. Thanks!
    My fabric has a large floral pattern with a horizontal repeat of 30 cm positioned centrally on the fabric. There will be a lot of waste when joining cut lengths to make sure the pattern actually matches along the seams. Do I calculate number of widths required based on the actual width of the fabric (150 cm) or the width between the centres of the pattern closest to the fabric edges (120 cm)?
    Sew Helpful
    Your width measurement for the calculations is the usable width (what it will be when joined). A standard width is approx 137cm, sometimes a standard pattern gets printed on wider fabric that leads to wastage when joining, also have you check if  it is a half drop pattern repeat?

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